JP2020085768A - Communication device, communication system - Google Patents

Abstract

To enhance accuracy of position determination and distance measurement using wireless communication.SOLUTION: A master device 10 includes a transmission-and-reception circuit 102, a mobile device position estimation section 103, and a correction value calculation section 104. The transmission-and-reception circuit 102 transmits a command Cm to transmit first radio waves Rs including first information indicating a transmission source to each of one or more slave devices. The transmission-and-reception circuit 102 receives the first radio waves Rs and second radio waves Rk including second information Rkj indicating, for each slave device, a first intensity Rs1 that is the reception intensity of the first radio waves Rs at a specific position. The correction value calculation section 104 obtains a correction value Cr for each slave device by comparing a second intensity Rs2 and a standard value Ref of the second intensity Rs2 for each slave device. The second intensity Rs2 is the reception intensity of the first radio waves Rs at the transmission-and-reception circuit 102. The mobile device position estimation section 103 estimates the specific position on the basis of values obtained by correcting the first intensity Rs1 using the correction value Cr for each slave device.SELECTED DRAWING: Figure 2

Description

The present invention relates to a technique for identifying a position by using wireless communication.

A crime prevention system is known in which bidirectional wireless communication is performed between an in-vehicle device and a portable device to prevent theft. For example, the security system uses wireless communication to perform mutual authentication between an in-vehicle device and a portable device and to measure a distance from the in-vehicle device to the portable device (hereinafter also referred to as “distance measurement”). The portable device is an object of distance measurement (hereinafter, also referred to as “distance measurement object”) when viewed from the in-vehicle device.

The on-vehicle device controls the vehicle equipped with the on-vehicle device, for example, locks/locks the vehicle door, provided that mutual authentication is established and the measured distance (hereinafter, also referred to as “measured distance”) is equal to or less than a predetermined value. Allows unlocking and starting of the engine. This is because, when locking/unlocking the vehicle door or starting the engine, the user carrying the portable device is usually close to the vehicle.

If the measured distance exceeds the predetermined value even if mutual authentication is established, mutual authentication is an illegal means, for example, a so-called relay attack technique in which a wireless relay device is interposed between the vehicle and the portable device. May have been realized by. Even if the user carrying the portable device is away from the vehicle, a person who does not carry the portable device may try to lock/unlock the vehicle door or start the engine close to the vehicle. It is advantageous to use the measured distance from the viewpoint of preventing the vehicle from being controlled by such an illegal means.

For example, in the technique described in Patent Document 1, the measurement distances from a plurality of locations near the vehicle to the portable device are obtained using wireless communication, and the range in which the portable device is located (hereinafter, also simply referred to as “position”) is specified. Technology is introduced.

International Publication No. 2016/143268

For example, the reception intensity of the wireless communication transmitted from the inside of the vehicle in the portable device is transmitted to the in-vehicle device from the portable device, and the in-vehicle device calculates the measurement distance based on the reception intensity.

However, in order to calculate the measurement distance from the reception strength, it is premised that the transmission strength of the wireless communication to be transmitted is known. However, even if the transmission intensity of the transmitter itself is known, it is assumed that an element that attenuates the radio field intensity exists around it. It is also assumed that the transmission intensity of the transmitter itself may change. The presence of such an element and the fluctuation of the transmission intensity may impair the accuracy of distance measurement and the determination of the position.

Therefore, an object of the present invention is to provide a technique for improving the accuracy of position determination and distance measurement using wireless communication.

A communication device according to a first aspect of the present invention transmits a command to cause each of at least one transmitter to transmit a first radio wave including first information indicating a transmission source, and the first radio wave at a specific position. A second radio wave including second information indicating the first strength, which is the reception strength of each of the transmitters, and a transceiver circuit for receiving the first radio wave, and the transmission and reception of the first radio wave transmitted for each transmitter. A memory for storing a reference value of the second intensity, which is the reception intensity in the circuit; a correction value calculation unit for calculating a correction value indicating the difference between the second intensity and the reference value for each transmitter; A communication device including a position estimation unit that estimates the specific position based on a value obtained by correcting the first intensity with the correction value for each time.

A communication apparatus according to a second aspect of the present invention is the first aspect, wherein the second intensity is larger than a second value obtained by adding a non-negative first value to the reference value, or When the second intensity is smaller than the fourth value obtained by subtracting the third non-negative value from the reference value, the correction value is the value obtained by subtracting the second intensity from the reference value. The correction value is 0 when the second intensity is not less than the fourth value and not more than the second value. The specific position is estimated based on a value obtained by adding the correction value to the first intensity for each transmitter.

The communication apparatus according to the third aspect of the present invention is the second aspect, wherein the first value is 0 and/or the second value is 0.

A communication device according to a fourth aspect of the present invention is any one of the first to third aspects, and further includes the at least one transmitter.

A communication apparatus according to a fifth aspect of the present invention is any one of the first to fourth aspects, wherein the at least one transmitter is a plurality of the transmitters.

A communication apparatus according to a sixth aspect of the present invention is any one of the first to fifth aspects, wherein the first radio wave is a UHF band radio wave.

A communication system according to a seventh aspect of the present invention includes the communication device according to any one of the first to sixth aspects, and a portable device that receives the first radio wave and transmits the second radio wave. Have.

According to the first aspect, the second aspect, the third aspect, and the fourth aspect, the first intensity used for estimating the specific position is corrected by the correction value indicating the difference between the second intensity and the reference value. Therefore, the influence of the variation in the transmission intensity from the transmitter on the distance measurement is reduced. Therefore, the accuracy of distance measurement and determination of a specific position is improved.

According to the fifth aspect and the sixth aspect, the accuracy of distance measurement and determination of a specific position is improved.

According to the seventh aspect, the accuracy of the position determination of the portable device and the accuracy of distance measurement are improved.

It is a schematic diagram which illustrates arrangement|positioning of a communication apparatus. It is a block diagram which illustrates the structure of a main|base station. 6 is a flowchart illustrating the operation of the embodiment. 9 is a flowchart illustrating the calculation of a correction value.

<Overall structure>
FIG. 1 is a schematic diagram illustrating an arrangement of two communication devices. The first communication device 1 is mounted on the vehicle body 9. The first communication device 1 includes a master device 10 and slave devices 11, 12, and 13. The base unit 10 has a transmission/reception function. In this embodiment, since the functions of the slaves 11, 12, and 13 are related only to the transmission function, it can be said that these functions as a transmitter. The first communication device 1 is applied to, for example, a body control module (hereinafter also referred to as “BCM”) which is an in-vehicle device. The second communication device 2 is provided in, for example, a portable device called fob or FOB. Hereinafter, the case where the second communication device 2 is the portable device 2 will be described as an example.

In FIG. 1, the slaves 11, 12, and 13 are located near the right front door, near the left front door, and near the rear trunk, respectively. Of course, the slaves 11, 12, and 13 may be arranged at positions other than the above positions. The case where the main|base station 10 is arrange|positioned near the center console was illustrated. Although the case where the portable device 2 is located outside the vehicle body 9 is illustrated, the case where the portable device 2 is located inside the vehicle may be assumed.

A signal in the UHF band (for example, 0.3 to 3 GHz) (hereinafter, also referred to as “distance measurement signal”) is transmitted from the slaves 11, 12, and 13. The mobile device 2 receives the distance measurement signal and transmits the reception intensity to the master device 10. The master device 10, the slave devices 11, 12, 13 and the portable device 2 constitute a communication system 3.

FIG. 2 is a block diagram illustrating the configuration of the master device 10. The base unit 10 includes a control unit 100, an antenna 101, a transmission/reception circuit 102, a portable unit position estimation unit 103, a correction value calculation unit 104, and a memory 105.

The transmission/reception circuit 102 transmits the command Cm via the antenna 101. The command Cm causes each of the slaves 11, 12, and 13 to transmit the first radio wave Rs. The first radio wave Rs includes the first information Rsj indicating the transmission source and functions as a distance measurement signal. The command Cm is transmitted from the control unit 100 to the transmission/reception circuit 102, for example.

The transceiver circuit 102 receives the first radio wave Rs and the second radio wave Rk via the antenna 101. The second radio wave Rk includes the second information Rkj. The second information Rkj indicates the reception intensity (hereinafter also referred to as “first intensity”) Rs1 of the first radio wave Rs received by the mobile device 2 for each of the slaves 11, 12, and 13.

The transmitter/receiver circuit 102 includes the first information Rsj included in the first radio wave Rs transmitted for each of the slaves 11, 12, and 13 and the first radio wave Rs received by the master device 10 (more specifically, the transmitter/receiver circuit 102). The reception intensity (hereinafter also referred to as “second intensity”) Rs2 is transmitted to the correction value calculation unit 104. The transmission/reception circuit 102 transmits the second information Rkj included in the second radio wave Rk to the portable device position estimation unit 103.

The memory 105 stores the reference value Ref for each child device having the second strength Rs2. The reference value Ref is transmitted from the memory 105 to the correction value calculation unit 104. The correction value calculation unit 104 compares the second intensity Rs2 and the reference value Ref for each of the slave units 11, 12, 13 and obtains the correction value Cr for each of the slave units 11, 12, 13.

The mobile device position estimation unit 103 obtains the measurement distance based on the value obtained by correcting the first intensity Rs1 with the correction value Cr for each of the slave devices 11, 12, and 13, and estimates the position of the mobile device 2. That is, the reception intensity (first intensity) Rs1 of the first radio wave Rs at the specific position is corrected with the correction value Cr, and the specific position is estimated based on the corrected value. The correction value Cr is obtained from the second intensity Rs2 and the reference value Ref.

The control unit 100, the portable device position estimation unit 103, the correction value calculation unit 104, and the memory 105 can be individually configured as circuits. The control unit 100, the portable device position estimation unit 103, the correction value calculation unit 104, and the memory 105 may be realized by one microcomputer.

FIG. 3 is a flowchart illustrating an operation of estimating a specific position (here, the position of the portable device 2) (hereinafter, “position estimation operation”) in this embodiment. The flowchart represents the operations of the master device 10, the slave devices 11, 12, and 13 and the portable device 2 in parallel.

After starting the position estimation operation, first, in step S101, the parent device 10 searches for the portable device 2. In this search, a so-called wake-up signal for canceling the sleep state of the portable device 2 can be adopted (a solid arrow pointing from step S101 to step S201 in the figure). The portable device 2 that has detected the search from the master device 10 responds to the master device 10. (Step S201). In this response, an acknowledge signal for the wakeup signal from base unit 10 can be adopted (a broken line arrow from step S201 to step S101 in the figure).

The parent device 10 determines whether the portable device 2 is detected in step S102. For the determination, for example, whether or not the master device 10 has received the acknowledge signal within a predetermined time after transmitting the wakeup signal can be adopted.

When the determination is negative (when the portable device 2 is not detected), the process returns to step S101. When the determination is affirmative (when the portable device 2 is detected), the process proceeds to step S103.

In step S103, the master unit 10 instructs the slave units 11, 12, 13 to transmit the first radio wave Rs. Specifically, such an instruction can be realized by transmitting the command Cm (a solid arrow pointing from step S103 to step S110 in the figure) as described above. The transmission of the command Cm is performed from the transmitting/receiving circuit 102 via the antenna 101 as described above.

Receiving the command Cm, each of the slaves 11, 12, and 13 transmits the first radio wave Rs including the first information Rsj indicating that it is the transmission source in step S110. This means that the first radio wave Rs is transmitted to both the parent device 10 and the portable device 2 (solid arrow pointing from step S110 to steps S104 and S202 in the figure).

The base unit 10 and the portable unit 2 receive the first radio wave Rs. The main|base station 10 measures the 2nd intensity|strength Rs2 for every subunit|mobile_unit 11,12,13 in step S104, and also acquires the 1st information Rsj. Such processing is performed in the transmission/reception circuit 102. In step S202, the portable device 2 measures the first strength Rs1 of each of the slave devices 11, 12, and 13.

After the step S104 is executed, the main|base station 10 calculates the correction value Cr which shows the difference between 2nd intensity|strength Rs2 and reference value Ref for every subunit|mobile_unit 11,12,13 in step S105. Such processing is performed in the correction value calculation unit 104. Step S105 includes a plurality of flows, which will be described later in detail with reference to FIG.

The portable device 2 transmits the first intensity Rs1, specifically, the second radio wave Rk to the parent device 10 in step S203 after step S202 is executed (solid arrow pointing from step S203 to step S106 in the figure). The base unit 10 receives the second radio wave Rk. In step S106, the parent device 10 corrects the first intensity Rs1 for each of the child devices 11, 12, 13 indicated by the second information Rkj included in the second radio wave Rk. For example, the correction value Cr is added to the first intensity Rs1. Such processing is performed by the portable device position estimation unit 103.

After execution of step S106, base unit 10 estimates the position of portable device 2 in step S107. Specifically, the position of the portable device 2 is estimated based on the value obtained by correcting the first intensity Rs1 with the correction value Cr. Such processing is performed by the portable device position estimation unit 103. Since such estimation technology itself is well known, detailed description thereof will be omitted.

FIG. 4 is a flowchart illustrating the content of the process of step S105 of FIG. 3, that is, the calculation of the correction value Cr. However, this flowchart shows the process of calculating the correction value Cr in one child device, and the process is performed for each child device. This flowchart shows a certain child device, and an example is shown in which the second strength Rs2 is expressed using the received strength RSSI (Received Signal Strength Indicator). The reference value Ref is also set for each child device, and is stored in the memory 105 at the time of factory shipment, for example.

The reference value Ref is set assuming the situation at the time of factory shipment. Specifically, for example, the ambient temperature of the slaves 11, 12, and 13 is a predetermined temperature, there is no element that interferes with the propagation of radio waves in their vicinity, and the transmission intensity of the first radio wave Rs transmitted from each is It is assumed that the situation is maintained, and the second intensity Rs2 in the situation is set as the reference value Ref.

Even if the transmission intensity of the first radio wave Rs is maintained, both the first intensity Rs1 and the second intensity Rs2 are lower as the ambient temperature is higher, and if there is an element that interferes with radio wave propagation in the vicinity of the slave unit, Both the strength Rs1 and the second strength Rs2 decrease. In other words, both the ambient temperature being higher than the predetermined temperature and the fact that an element that interferes with the propagation of the radio wave is present near the slave unit make the transmission intensity of the first radio wave Rs apparently small. Become.

If the second strength Rs2 is larger than the reference value Ref by a certain deviation, it is considered that the first strength Rs1 is also deviated to the same extent as in the situation at the time of factory shipment. For example, considering the first intensity Rs1 and the second intensity Rs2 in dBm, it can be considered that the first intensity Rs1 is biased due to the difference between the second intensity Rs2 and the reference value Ref.

In step S105a, the first value δ1 is introduced, and it is determined whether the second strength Rs2 is larger than the second value (Ref+δ1). The first value δ1 is a non-negative value (0 or a positive value), and is the width of the dead zone for the second strength Rs2 when the second strength Rs2 is larger than the reference value Ref.

If the result of the determination in step S105a is affirmative (if Rs2>Ref+δ1), the process proceeds to step S105d, and the correction value Cr is set to a value (Ref-Rs2) obtained by subtracting the second intensity Rs2 from the reference value Ref. To be done. Such a process corresponds to a case where the transmission intensity of the first radio wave Rs apparently increases, and is assumed to be, for example, a case where the ambient temperature of the slave unit is lower than a predetermined temperature.

By adding such a correction value Cr to the first strength Rs1 in step S106, the apparent increase in the transmission strength of the first radio wave Rs is corrected.

If the result of the determination in step S105a is negative, the process proceeds to step S105b. In step S105b, the third value δ2 is introduced, and it is determined whether the second intensity Rs2 is smaller than the fourth value (Ref-δ2). The third value δ2 is a non-negative value (0 or a positive value), and is a dead zone width for the second intensity Rs2 when the second intensity Rs2 is smaller than the reference value Ref.

If the determination result in step S105b is affirmative (Rs2<Ref-δ2), the process proceeds to step S105d. This process is a process corresponding to the case where the transmission intensity of the first radio wave Rs apparently decreases. For example, when the ambient temperature of the slave unit is higher than a predetermined temperature, or when the element that causes a radio wave propagation obstacle is the slave unit. It is assumed that it exists in the vicinity of.

By adding such a correction value Cr to the first strength Rs1 in step S106, the apparent decrease in the transmission strength of the first radio wave Rs is corrected.

If the result of the determination in step S105b is negative, the process proceeds to step S105c, and the correction value Cr is set to 0. In this processing, the transmission intensity of the first radio wave Rs is within the dead zone (the fourth value (Ref-δ2) or more and the second value (Ref+δ1) or less), and the situation around the slave unit is the same as that at the time of factory shipment. It is assumed that they are about the same.

The correction value Cr is set in steps S105c, S105d, and S105e, and the process of step S105 ends.

In this way, the correction value Cr reduces the influence of the surroundings of the slaves 11, 12, and 13 on the apparent transmission intensity of the first radio wave Rs. Therefore, the accuracy of position determination and distance measurement using wireless communication is improved.

Not only the influence of the surroundings of the slaves 11, 12, 13 but also the transmission intensity of the first radio wave Rs of the slaves 11, 12, 13 itself fluctuates from the time of factory shipment, the effect of the embodiment is obtained. It is clear that you can get it.

<Transformation>
Different structures are not necessarily required for the parent device 10 and the child devices 11, 12, and 13. For example, when an abnormality occurs in the parent device 10, any one of the child devices 11, 12, and 13 may function in place of the parent device 10.

The first radio wave Rs may be transmitted from at least one slave 11, 12, 13. In other words, at least one slave 11, 12, 13 may function as a transmitter. This is because the accuracy of distance measurement can be improved for each child device.

A plurality of slaves 11, 12, 13 may function as transmitters. This is because the accuracy of position determination is improved by using a plurality of first intensities Rs1.

Adopting the UHF band as the frequency band of the first radio wave Rs is advantageous from the viewpoint of improving the accuracy of position determination. This is because radio waves in the UHF band have high straightness.

The operations of steps S101, S201, and S102 may be omitted. For example, steps S103 and S110 may also serve as step S101, and the first radio wave Rs may function as a wakeup signal. Similarly, step S203 may serve as step S201 and step S106 may serve as step S102.

When a positive determination result is obtained in step 105a, the value (Ref+δ1) may be adopted instead of the reference value Ref in step S105d. When a positive determination result is obtained in step 105b, a value (Ref-δ2) may be adopted instead of the reference value Ref in step S105d.

The first value δ1 and/or the third value δ2 may be zero. The case where the first value δ1 is 0 corresponds to the case where the dead zone is not provided when the second intensity Rs2 is larger than the reference value Ref. The case where the third value δ2 is 0 corresponds to the case where the dead zone is not provided when the second intensity Rs2 is smaller than the reference value Ref.

When both the first value δ1 and the third value δ2 are 0, the determinations shown in steps S105a and S105b are unnecessary. This is because it corresponds to the case where the dead zone is not provided. In this case, if Rs2=Ref, the processes of steps S105c and S105d produce the same result. Therefore, step S105c is also unnecessary. After all, when both the first value δ1 and the third value δ2 are 0, step S105 only needs to execute step S105d.

The respective configurations described in the above-described embodiment and each modification can be appropriately combined unless they contradict each other.

Although the present invention has been described in detail as described above, the above description is an example in all aspects, and the present invention is not limited thereto. It is understood that innumerable variants not illustrated can be envisaged without departing from the scope of the invention.

1 (first) communication device 2 portable device (second communication device)
3 Communication system 11, 12, 13 Remote unit (transmitter)
102 transmitter/receiver circuit 103 (portable device) position estimation unit 104 correction value calculation unit 105 memory

Claims (7)

A command for transmitting a first radio wave including first information indicating a transmission source is transmitted to each of at least one transmitter, and a first intensity, which is a reception intensity of the first radio wave at a specific position, is set to each transmitter. A transmission/reception circuit that receives the second radio wave including the second information shown in FIG.
A memory for storing a reference value of a second intensity, which is a reception intensity of the first radio wave transmitted by each of the transmitters in the transmission/reception circuit,
A correction value calculation unit that calculates a correction value indicating the difference between the second intensity and the reference value for each of the transmitters;
A communication device comprising: a position estimation unit that estimates the specific position based on a value obtained by correcting the first intensity with the correction value for each of the transmitters. The communication device according to claim 1,
When the second intensity is larger than a second value obtained by adding a non-negative first value to the reference value, or when the second intensity is smaller than a fourth value obtained by subtracting a non-negative third value from the reference value. At this time, the correction value is a value obtained by subtracting the second intensity from the reference value,
When the second intensity is the fourth value or more and the second value or less, the correction value is 0,
The communication device, wherein the specific position is estimated based on a value obtained by adding the correction value to the first intensity for each of the transmitters. The communication device according to claim 2, wherein
A communication device, wherein the first value is 0 and/or the second value is 0. The communication device according to any one of claims 1 to 3,
A communication device further comprising the at least one transmitter. The communication device according to any one of claims 1 to 4, wherein:
A communication device, wherein the at least one transmitter is a plurality of the transmitters. The communication device according to any one of claims 1 to 5, wherein:
The communication device, wherein the first radio wave is a UHF band radio wave. A communication device according to any one of claims 1 to 6,
A communication system comprising: a portable device that receives the first radio wave and transmits the second radio wave.

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